Replaceable drill bit



June 9, 1959 1.. BROWN, JR 2,890,022

REPLACEABLE DRILL BIT Filed Sept. 3, 1957 l v INVENTOR. LOTHROP LEE BROWN,JR.

United States Patent REPLACEABLE DRILL BIT Lothrop L. Brown, Jr., Long Beach, Calif. Application September 3, 1957, Serial No. 681,514

4 Claims. (Cl. 25576) 7 This invention relates to well drilling apparatus and more particularly to an improved self-aligning drill bit which is replaceable while the drill string remains in the hole. Y I .In the drilling of oil wells and other bore holes deep in the earth considerable time is lost in the drilling operanon due to the time required to periodically change the drill bit. That is, when the bit has been dulled or when a different bit is required due tochange of formation, it is necessary in the present state of the art to make a complete trip out of and into the hole. Thus, in order to changethe bit all of the drill pipe must .be removed, a difierent bit installed at the end of the string, and the string replaced in the hole. The disadvantages of such an operation are obvious especially considering the length of time involved in a trip into a hole of considerable depth; Accordingly, it is an object of the present invention to provide a well drilling bit apparatus which can be placed at and removed from the bottom of a drill string without removing the drill string from the hole. I It is another object of the present invention to provide adrill bit apparatus which can be placed in the drill pipe at the surface of the hole and will descend down the drill pipe and be aflixed in drilling position at the bottom of-the string.

It is a further object of the present invention to provide a drill bit apparatus which can be released from drilling position and removed from the 'drill string from the surface of. the hole without removing .the drill pipe fromthe hole.

. It is a still further object of the present invention to provide a drill bit apparatus which may be inserted into drilling. position and removed therefrom through the drill pipe but which-bores a hole having a diameter greater than the outside diameter of the drill pipe.

Still another object of the present invention is to provide .a bottom hole replaceable drill bit apparatus which will maintain a straight or axial direction of drilling without lateral drift or wandering at the bottom of the hole.

A replaceable drill bit apparatus in accordance with the present invention comprises a drill bit of fixed diameter which diameter is less than the inside diameter of the drill pipe to which the bit is to be attached. The drill bit is aflixed to a generally cylindrical body having a diameter less than the inside diameter of the drill pipe. The drill bit body carries a plurality of reamer cutters which are retractable into the body to a diameter equal to or less than the diameter of the bit. The rearners are expandable to a diameter equal to the diameter of the hole being drilled. Means are provided for engage ing the drill bit body with the drill string 'by allowing the apparatus to descend downward within the drill string. Theldrill bit apparatus is engaged such that the body is non-rotatable and immovable with respect to thedrill string and such that the bit and reamers extend below the bottom of the drill string in drilling position. Means are also provided for releasing the drill bit body from such engagement and retrieving the drill bit apparatus through the drill string.

The novel features which are believed to be characteristic of the present invention, both as to its organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawing. It is to be expressly understood, however, that the drawing is for the purpose of illustration and example only, and is not intended as a definition of the limits of the invention.

Figure 1 is a longitudinal view partly in section showing the bit apparatus in drilling position engaged with the drill string in a drill hole;

Figure 2 is a partial view corresponding to Figure 1 of the-longitudinal retaining means in the released condition with the retrieving means in operable position;

Figure 3 is a sectional view taken along line 33 of Figure 1; and

Figure 4 is a sectional view taken along line 4-4 of Figure 1;

Figure 5 is a sectional enlarged partial view of a reamer as aflixed to the body.

Referring now to the drawing and particularly to Figure l, a presently preferred embodiment of the present invention comprises a removable drill bit body 10 which is hollow and substantially cylindrical in configu-' ration. The largest diameter of the body 10 is substantially equal to, but less than, the inside diameter of the drill pipe which is used to make up the drill string. A tubular body 11 into which the drill bit body 10 is engageable, as described hereinafter, is generally vertically disposed with a customary upper threaded box 12 into which-may be screwed a service or tool joint for connection of the drilling apparatus at the end of the drill string 16. The tubular body 11 has inside and outside diameters substantially equal to the inside and outside diameters of the drill pipe 16 and has a plurality of radially extending protrusions 18, described in further detail hereinafter, which have a radius substantially equal to the radius of the hole being drilled. Thus, the outer surface 19 of the protrusions 18 as shown in Figures 1, 2 and 3 bear against the wall of the hole and act as a guide bearing to maintain the bit in axial alignment during rotation.

The drill bit body 10 is slidably mateable with the tubular body 11 and means are provided for preventing relative rotation between the bodies when the drill bit is in the operative position as shown in Figure 1. Nonrotating interengagement is obtained in this embodiment by forming the drill bit body 10 in two sections, the upper section 20 and the lower section 21. The upper section 20 is tubular with an out-side diameter substantially equal to the inside diameter of the tubular body 11 and has a partially closed upper end 23 to which a grappling cone 24 is affixed. A plurality of openings 25 are provided through the end 23 of the body section 20, or the end surface is formed as a spider, to allow the free circulation of fluid through the end 23 and into the drill bit body 10. The end surface 23 of the upper body section 20 is positioned proximate the lower end of the protrusions 18 and the body section 20 extends downward to .a position a substantial distance above the lower end 26 of the tubular body 11. The lower end of the upper body section 20 is serrated or otherwise formed to provide a series of serrations 27 which extend around the circumference of the body '20. The serrations 27 of the body are tapered and are mateable with a like series of 'serrations 28 formed upon the upper surface of a collar :29

-3 which "is 'aflixed to the inner surface of the tubular 'body 11 beneath the upper section 20 of the drill bit body 10.

The lower section .21 .of the drill bit body 10 is atfixed to the upper.'seetioh 2i) in *this embodiment by forming the outside diameter f the lowerjsect'ion equal "to the inside diameter of the uppersection and collar 29 along a longitudinal distance of reduced wall thickness of the upper :section. Thus, a substantial length of the lower section 21 forms a s'lipfit partially intothe 'upper section to a shoulder '31 "formed by the reduced wall thickness. The lower section 21 is 'laifiir'ed to the upper section 'by welding or "other means known "to the art, such that upward forces or rotational forces on the lower section 21 "are transmitted to the upper section through the Welding 'andthe shoulderi31. The upper end of the lower body section is partially closed and is provided with means for restricting theflow of fluid t'herethrough. That is, in this embodiment a flapper valve of the type well known to the art is provided to'allowthefreedlowof fluid i'n -the downward direction, but to restrict the flow of fluid in the-upward direction. Thus, a hinged plate 33 is a'flixed at the upper-end of the lower section 21 by means of a hinge 3'6 and a lock ring 34. Openings 45 of a predetermined diameter are provided through the plate to allow :the restricted flow of "fluid upward through the plate. During the free descent of the body through a column of fluid within the drill string, as described hereinafter, the flow of fluid "through the "interior 35 of the body 10 will close the "flapper plate 33 "to allow fluid flow through 'the openings only, to govern the rate of descent of the body. However, if the body is raised with- 'm the drill string through a column of fluid the relative direction of fluid' flow-through the body is downward and 'the fl'apper will be opened-to allow free flow of fluid through 'the'upper'en'd of the lower section 21 and thus through the body 10.

In the assembled position of the upper body section 20 and lower body section 21 the wall thickness of the lower section is increased su'fliciently 'to provide a mountingmeans for a pflot bit 40 anda pair=of retractable reamer cutters 41 and 42. Thus, from a longitudinal position proximate the lower end 26 of the tubular body 1 1 the lower body section 2-1 .becomes a substantially solid cylindrical body provided, however, with a fluid flow path 43 extending to the pilot bit and a fluid bypass path which is two fluid'ports 44 in this embodiment. Thus, referring to Figures "1 aud t, a pilot bit'40 of the tricone roller bit type is aflixed at the lower end of the lower body section. The bit is of the type Well known to the art and is of fixed boring diameter. The diameter of the bit which is used is substantially equal to the inside diameter of the collar 29 and is less than the inside diameter of the drill string 16. The fluid path 43 through the lower body section communicates with the :flui'd .ports of the bit to furnish circulation fluid to the bit in the manner well known to the art.

A .pair of diametrically opposed pockets or recesses 46 are provided in the lower'body section 20 above the bit 40 to accommodate the retractable reamer cutters 41tand 42. That is, a pair of roller reamer cutters of .the type Well known to the art are p-ivotally mounted in the body upon the mounting pins 47 which are pivotally *aflixed to the body. The reamer cutters 41, 42 are freely rotatable :about the respective shafts 48 which are in turn affixed to the mounting pins 47 for pivotal movement with respect to the body. A ball bearing 49 is p'ositionetd at the end of each shaft 48 to act as a roller and thrust bearing with respect to the cutter and 'Shaftto iusureLfIee rotation. The reamers are afiixed rotatably upon the respective shaft 48 by means such as the sets'crew "48.1 which extends radially through the wall of'theireamer audint'o a circumferential groove 48.2 .inth'e :shaft 48. The .reamer-s are mounted .upon :mounting'pins to extend radially and to cut to the diameter of the well bore being drilled. Thus, the

reamer "cutters extend the diameter of the well bore from that drilled by the pilot bit 40 to the full required hole diameter 50. Means are provided to yieldably urge the reamers to the outward cutting position as shown in Figure 1. Spring, hydraulic, or torque means of the type known to the art may be used to urge the reamers outward althoughinthis. embodiment springs 51 are used. A shield 52 is affixed to the reamer mounting means to substantially enclose the 'reamers in the retracted position-and to furnish a means for retracting the reamers when the drill bit body 10 is within the tubular body 11 or "thedrill string 16. The pivot point of the reamers are positioned within "the body such that when the reamers are pivoted downward and into the recesses 46 the reamers and shields are completely contained within the diameter of the drill bit body 10 in order that they can pass through the drill string. Thus, the reamers are retractable to a diameter less than the inside diameter of the .drill string. A downwardly and outwardly extending taper 53 is formed on the lower inside edge of the collar 29 to provide a retracting force upon the reamers when the drill bit body is withdrawn upward through the tubular body as described hereinafter. At the fully expanded position'of the reamers'thereamer assembly is in bearing contact with the body 10 at the shoulder 54 which restricts the 'rca'ruers to a substantially -transverse plane "and transmits any load upon the reamers to the body.

Means are provided for engaging the drill bit body IOWithin the tubular body 11 toprevent relative "longitudinal movement of the drill bit apparatus when in the assembled and operative condition shown "in Figure l. Thus, referring to Figures 1, 2 and 3, the protrusions 18 define chambers 55 extending radially beyond the inside diameter of "the tubular body 11 and above the upper end '23 "of the drill bit body 10. A plurality of holding devices are positioned within the chambers to form longitudinal locking means which can be disengaged. In the embodiment shown a locking lever 56 is pivotally mounted in each protrusion. The lever is of substantial weight and 'is of such length as to be mateabl'e with an engaging shoulder 57 at the upper end 23 of the drill bit body in the assembled position. Means are provided for urging the levers radially inward "at the lower end thereof to the latching position. In this embodiment the weight of the lever is used to achieve this movement by pivoting the lever at a point radially inward of the vertical *centerline of the lever. That is, each lever-is pivotally mounted upon a mounting pin 58 positioned proximate the upper end of the .lever but to the radially inward side of the longitudinal centerline of the lever. Thus, the weight of the lever will force the lower end of the lever inward tothe engaging position shown in Figure 1.

The means for retrieving the drill bit apparatus is shown in the non-engaged position in Figure 1 and in the engaged position in Figure 2. The retrieving grapple 60 comprises a cylinder substantially open at the lower'end and closed at the upper end but provided with fluid flow openings 61 at the upper end. The cylinder has an outside diameter substantially equal to the inside diameter of the tubular body 11 and an inside diameter suflicient to pass over the 'grapplingcone 24 on the drill bit body 10. A cable 59 is attached to the upper end of the grapple to retrieve it fromthe drill string. A pair of spring loaded grappling arms 62 are pivotally mounted Within the grapple cylinder substantially symmetrical about the centerline of the grappie. The grappling arms are substantially mateable with the cone '24 and are spring loaded by a spring '64 in tension which urges the arms together to a closed posi- 'tion as shown in Figure 3 in which the fingers 65 are in vertically holding contact with the grappling surface '66 of the cone -24.

Thus, in operation, referring to Figures 1 and 2, to

remove the drill bit apparatus from the assembled and drilling position shown in Figure l, the grapple 60 is lowered on the cable 59 into the drillstring. As the grapple moves downward fluid flows through the fluid openings 61 to allow downward progrms. The grapple passes beyond the protrusions 18 such that the outside diameter of the grapple cylinder forces the locking levers 56 outward and moves the levers out of engagement with the drill bit body 10. As the grapple arms 62. tongs strike the inclined surface of the cone 24 they are forced outward against the action of the spring 64. Further downward movement of the grapple and tongs allows the fingers 65 to pass beyond the inclined face of the cone and to be pulled inward by the spring 64 to engage the grappling surface 66 of the cone as shown in FigureZ. The cable is thenraised to raise the drill bit apparatus out of the hole. As the drill bit body is raised the reamer assemblies, i.e., the reamer shields 52 strike the lower end of the tubular body 11 and are forced inward against the action of the expanding springs 51 by the tapered surface 53 on the collar 29. As the drill bit body continues to be raised the reamers are thus retracted into the recesses 46 at a diameter less than the inside diameter of the tubular body 11 and the drill string 16. Thus, the entire drill bit body 10, including the bit 40 and reamers 41 and 42, will pass upward through the drill string. During upward passage of the drill bit body the flapper plate 33 pivots downward to allow free passage of the drill bit apparatus through fluid in the drill string. Thus, the drill bit apparatus is raised through the drill string to the surface of the hole.

In order to place the drill bit apparatus in the operative position the drill bit apparatus with the reamers retracted is placed in the drill string at the surface of the hole with the gripple 60 removed from the string. The drill bit body 10 is allowed to fall freely down the drill string which contains circulation fluid. As the drill bit apparatus falls within the string the flapper valve 33 closes by pivoting upward and fluid must pass relatively upward through the body by passing through the openings 45 in the flapper plate. Since the openings are somewhat restrictive the descent of the apparatus will be at a controlled rate. As the drill bit body 10 falls into the position shown in Figure l the reamers pass beneath the end of the tubular body 11 and are free to move outward to the expanded position and will be forced outward by the progress of the pilot bit 40 as the hole is drilled. When the body 10 reaches the position of Figure 1 the serrations 27 on the body 10 and the serrations on the tubular body 11 will mate and prevent relative rotation of the drill bit body 10 within the tubular body 11. Similarly, as the upper end 23 of the body 10 passes beneath the locking levers 56 the levers will pivot inward at the lower end to engage the drill bit body 10 and prevent relative longitudinal movement of the drill bit body within the tubular body 11. The drill bit apparatus is thus in the assembled drilling condition. The drill string is then rotated to bore the required hole. The pilot bit 40 will drill a pilot hole 30 which is expanded to the desired full hole diameter by the following reamer cutters which have been forced to the fully opened position. The operation utilizing a pilot bit followed by reamer cutters directly above will maintain the axial alignment of the hole being drilled and prevent the lateral drift or wandering a hole bottom which is encountered when a single bit is used. In addition, the protrusions 18 have a bearing surface 19 equal to the hole diameter 50 which bear upon the sides of the hole to act as an alignment bearing above the drilling apparatus to further insure aligned and straight progress of the drilled hole.

While the present invention has been particularly described in connection with the method of drilling wherein the drill string is rotated it is equally applicable to the method of drilling wherein the drill string remains stationary while the drill bit is rotated by means of a turbine or the like contained within the drill bit body.

' Thus, what has been disclosed is an improved drill bit apparatus which can be inserted into and removed from a drill string in a well bore without removing the drill string from the bore. The apparatus of the present invention further insures true alignment of the hole to be drilled without lateral drift from the axial course desired.

What is claimed is:

1. A replaceable drill bit apparatus to be affixed at the end of a tubular drill string comprising: a substantially vertically extending tubular body, said body being affixed at the lower end of said tubular drill string substantially coextensive therewith; a generally cylindrical drill bit body removably engaged within said tubular body extending a substantial distance below the lower end thereof, said drill bit body having an outside diameter less than the inside diameter of said drill string and said tubular body; a drill bit of substantially fixed diameter afiixed at the lower end of said cylindrical body, said fixed diameter being less than said inside diameter of said drill string and said tubular body; a plurality of retractable reamer cutters affixed to said drill bit body below said tubular body, a plurality of mounting shafts upon which said cutters are mounted, means for pivotally aflixing said shafts upon said drill bit body whereby said cutters are expandable to a desired diameter of the well to be bored, which diameter is greater than said fixed diameter of said drill bit, said reamer cutters being retractable to a diameter less than said inside diameter of said drill string and said tubular body; and a plurality of protrusions extending radially outward from said tubular body to a diameter substantially equal to said diameter of the well, a releasable engaging lever in each of said protrusions, whereby said levers aflix said drill bit body against relative longitudinal movement with respect to said tubular body when said drill bit body is in said releasably engaged position, means for releasably affixing said drill bit body against relative rotational movement with respect to said tubular body, and means for releasing said levers and grappling said drill bit body from the surface of said well.

2. The apparatus of claim 1 wherein said releasing and grappling means includes a conical protrusion extending from the upper surface of said drill bit body, said conical protrusion being upwardly convergent and having an engaging shoulder therein, a grappling means, said grappling means including a substantially tubular body, said grappling body having an outside diameter substantially equal to, but less than the inside diameter of said tubular body, spring loaded tongs within said body, whereby said body disengages said levers and said tongs engage said protrusion, and a cable affixed to said grappling body extending from said surface.

3. A replaceable drill bit apparatus to be aflixed at the end of a tubular drill string comprising: a substantially vertically extending tubular body, said body being affixed at the lower end of said tubular drill string substantially coextensive therewith; a generally cylindrical drill bit body removably engaged within said tubular body extending a substantial distance below the lower end thereof, said drill bit body having an outside diameter less than the inside diameter of said drill string and said tubular body; a drill bit of substantially fixed diameter afiixed at the lower end of said cylindrical body, said fixed diameter being less than said inside diameter of said drill string and said tubular body; a plurality of retractable reamer cutters aflixed to said drill bit body below said tubular body, a plurality of mounting shafts upon which said cutters are mounted, means for aflixing said shafts upon said drill bit body whereby said cutters are expendable to a desired diameter of the well to be bored, which diameter is greater than said fixed diameter of said drill bit, means for biasing said cutters to said expanded position, said reamer cutters being retractable to a diameter less than said inside diameter of said drill string and said tubular body; and a. plurality of protrusions extending radially outward from said tubular body to a diameter substantially equal to said: diameter of the Well bore, a releasable engaging lever in each of said protrusions, whereby said levers aflix said drill bit body against relative longitudinal movement with respect to said tubular body when said drill bit body is in said neleasably engaged position, means for releasably aflixing said drill bit body against relative rotational movement with respect to said, tubular body, and means for releasing said levers and grappling, said drill bit body'from the surface of 'said well;

- 4, The apparatus of claim 3 wherein said releasing and grappling means includes a conical protrusion extending from the upper surface of said drill bit body, said conical protrusion: being upwardly convergent. and having engaging shoulder therein, a grappling means, said grappling means including a substantially tubular body, said grappling body having an outside diameter substantially equal to, but less than the inside diameter of saidtubular body, spring loaded tongs With-in said body, whereby said body disengages said levers andsaid tongs engage said protrusion, and a cable aflixed to said grappling body extending from said surface.

References Cited in the file, of this patent UNITED STATES PATENTS 2,046,106 Bozeman June 30, 1936 2,134,988 Stokes Nov. 1, 1938 2,330,083 SeWell Sept. 21, 194-3 

